Heat exchanger



F. W. OFELDT HEAT EXCHANGER Filed Aug. 26; 1927 March 17, 1933.

I 2 Sheets-Sheet l IT 20 5 v 20 3 11 6 INVINTO R F. W. OF ELDT HEATEXCHANGER Filed Aug. 26,

. March 17, 192.1.

1927 2 Sheets-Sheet 2 Patented Mar. 17, 1931 UNITED STATES FRANK W.OFELDT, 6F MOKEESPORT, PENNSYLVANIA HEAT nxcinlvenn Application filedAugust 28, 1927- Serial No. 215,558.

. as water boilers, steam boilers, and the like,

and more particularly to a heat exchanger ,8 of the coil type,particularly adapted for the heating of water.

It has heretofore been proposed in the art .to which the presentinvention relates to provide coil or tube heaters of the generalcharacter herein contemplated and com-. prising a main source of watersupply communicating with a plurality of tubes or coils dis osed in asuitable heating chamber. In such apparatus, there has, however, been nomeans for securing eflicient distribution of the liquid through thecoils or tubes, or for obtaining efficient circulation of the heatedwater throughout the entire system.

The present invention has for one of its objects the provision of anapparatus of this character so constructed that the liquid isefl'ectively caused to pass in divided or distributed condition throughthe heating coils or tubes provided for that purpose.

Still another object of the invention is to provide a construction suchthat in a predetermined portion or portions of the apparatus the wateris raised to a steam generating temperature while the water in the otherportions of the apparatus is being heated, the steam thus. generatedbeing utilized to produce a forced circulation throughout the heatingsystem with which the heat exchanger is utilized.

In the accompanying drawings there are shown for purposes ofillustration only, certain preferred embodiments of the presentinvention, it being understood that the drawings do not define thelimits of my invention as changes in the construction and operationdisclosed therein may be made with out departing either from the spiritof the invention of the scope'or my broader claims.

In the drawings,

Fig. 1 is a vertical sectional view with certain of the parts inelevation,- through one form ofheat exchanger constructed in accordancewith the present invention};

' Fig. 2 is a transverse sectional view on the line 11-11 looking in thedirection of the arrows; Fig. 3 is a view similar to Fig. 1 showing aslightly modified embodiment of the present invention; and, I

Fig. 4 is a detail sectional view on an enlarged scale of the safetylighter.

In carrying out the present invention, there may be provided a suitablecasing 2 mounted on a base 3 and communicating: at its upper portionwith a suitable outlet 4 for the escape of products of combustion.

-Extending centrally within the casing 2 is a tubular water receivingcasing 5 communicating at its lower end with a supply connection6through which the water to be heated is en plied to the apparatus. Atits upper end t e casing 5 communicates with a water outlet 7 leading tothe part of the system to which hot water is to be supplied. At asuitable point intermediate the connection 6 and the connection 7, thecasing is provided with a baiile plate 8 having a restricted orifice 9therein for the purpose hereinafter more fully pointed out.

Arranged within the heating compartment formed between the casings 2 and5 is a plurality of tubes or coils 10 of suitable construction, each ofthe tubes or coils preferably communicating at one end with the casing 5adjacent the oint of water inlet thereto at one side of t e baiile 8 andat the other end with the casing 5 adjacent the point of water outlettherefrom, and above the baflle 8.

One or more of these pipes or coils is of such construction that itprovides a greater, heating surface per unit of water than the othercoils or pipes, whereby with a constant heat transfer coefficient, thetotal heat transfer to the water passing therethrough is greater thanthe total heat transfer to the water passing through the other pipes orcoils. This condition may be effectively obtained either with anarrangement such as illustrated in Fig. 1 by the utilization of a coil11 having a greater over-all length than the other coils, or asindicated by Fig. 3by the provision of a coil 11, having a restrictionin the inlet thereof causing a less amount of water to flow through itunder given conditions than passes through the other heat transferunits.

With either formof the'apparatus, the parts are correlated and arrangedin such manner that in passing through the transfer unit 11 or 11, thewater is raised to such a temperature that steam is generated, thissteam being relieved through a nozzle '12 directed upwardly into theoutlet connection 7 in the general direction of flow there-.

through. This generated steam passing into the body of water acts toproduce in effect, an aerated column, the steam bubbles decreasing theeffective weight of the liquld per unit of pipe length whereby it tendsto rise and thus produce circulation in the system.

' gas supply line 17 The supply of gas maybe automatically or manuallycontrolled, there being illustrated in the drawings, a heat responsiveelement 18 adapted to operate a valve 19 to admit more or less gasdepending upon the temperature of-the water leaving the heater.

Arranged within the heating chamber and carried by the burner plate 3 isa ser es of distributors 20, each cooperating at its inner end with oneof the openings 13, and

suitably held on the burner plate in any desired manner as by fasteninbolts 21. Each of these distributors is 0 such construction as toeffectively break up and mstribute the gas supplied thereto from thenozzle 15, together with entrained a r, th1s being accomplished in theform lllustrated by the provision of transverse slits 22.

There may be provided a safetylightlng device, comprising a movablepilot tube 23 having its lower end constructed to form a valve 24operative in the gas supply hne 17 The upper end 25 of the safetyllghter 23 is directed inwardly and is adapted to extend into andthrough a nipple 26 on the side of the casing 2. It carrles at asuitable point intermediate its length a closure plate 27 adapted tocompletely'tclose the outer end of .the nipple 26, which ple constitutesthe only means of access or hght ng purposes to the interior of theheater. In operation, the safety hghter 23 1s swung to the right asviewed in Fig. 4, and thegas issuing from its upper end is lighted. It iis then swung into the position indicated in dotted lines in thisfigure, this movement being efiective for opening the supply line 17 forthe free passage of gas therethrough, which gas as it issues from thedistributors, is lighted within the heater. Should the operator fail tolight the safety pilot before swinging it into position, there is .nomeans of igniting the gas within the heater and consequently thepossibility of an explosion is obviated. In order to light it, it isnec-- essary to swing the safety valve out of its dotted line position,which shuts off the gas to the nozzle 15, and manipulate the partsthrough a new cycle as before described.

The construction illustrated in Fig. 3 corresponds to that shown in Fig.1 with the results in the generation of steam for the purposes referredto.

The ba'flie 8 serves a dual function in the construction illustrated, inthat it prevents free flow of water from the inlet 6 to the outlet 7thereby compelling passage of water through the heating units, andfurther in that it permits a limited circulation directly between theinlet and outlet which limited circulation is sufiicient to adequatelytake care of the heat transfer through the surface provided by thecasing 5 and thereby precludlng theformation of a steam pocket therein.

Certain advantages of the present invention arise from the provision ofan improved heat exchanging apparatus providing means for the heating ofwater in distributed condition while insuring thegeneration in limitedquantities of steam for circulation pur-' poses while precluding thegeneration of steam in all of the uni Still further advantages of theinvention arise from,the provision of a water heating boiler comprisinga series of units, the heater being provided with means insuring thepassage of water through these units.

Still other advantages of the invention arise from the revision of meansfor efiectively distributmgthe combustible mixture to thereby obtainefiicient flame conditions within the heater. I 4 1 Still otheradvantages arise from the provision of safety means for lighting theheater.

I claim: I I

1. Ina water heater, 9. central water sup-. ply-casmg"hav1ng a bafiletherein, an outer casing, a. plurality of water heating units.thepassage of only a each unit having its central casing at one itsoutlet connected between said casing, inlet connected to said side ofsaid baflle and to said central casing at the opposite side of saidbaflle, at least one of said units being constructed toinsure a greatertotal heat transfer for a given quantity of. water than the otherunits,' and means for heating said units. L

2. In a water heater, a' central water suppuly casing having a bafiletherein, said baffle having an opening of such size as to allow limitedquantity of outer casing, a pluunits between said water therethrough, anrality of water heating casings, each unit having its inlet connected tosaid central casing at one side of said baifle and its outlet connectedto said centralcasing at the opposite side of said bafile, at least oneof said units being longer than the others so as to generate steamtherein eflectlve for causing circulation of water in said other un1ts,and means for heating sald units.

Intestimony whereof I have hereunto set my hand.

FRANK W. OFELDT.

